python中存根文件(.pyi)的用途是什么? [英] What is the use of stub files (.pyi ) in python?

问题描述

我正在尝试了解 python 3 的较低级别的实现.子进程模块使用了一个名为 _posixsubprocess 的模块.我试图在我的系统中找到这个模块的位置，发现它是一个存根文件.

I am trying to understand the lower level implementations of python 3. There is one module named _posixsubprocess used by the subprocess module. I tried to find the location of this module in my system and found that it's a stub file.

由于我不知道存根文件是什么以及它们如何在较低级别实现，因此有人可以指导我吗?

Could someone guide me as I have no idea about what are the stub files and how are they implemented at the lower level?

推荐答案

_posixsubprocess

您引用的文件是用 C 编写的 Python 模块.它不是存根"文件.真正的实现可以在 Modules/_posixsubprocess 的标准库中找到.c.您可以通过查看 构建 C 和 C++ 来了解如何编写 C/C++ 扩展扩展.这应该有助于您理解 _posixsubprocess.c 中的代码.

_posixsubprocess

The file you are referencing is a Python module written in C. It's not a "stub" file. The real implementation can be found in the stdlib at Modules/_posixsubprocess.c. You can see how writing a C/C++ extension is written by having a look at Building C and C++ Extensions. This should help you understanding the code in _posixsubprocess.c.

为了将类型提示添加到该文件(它是用 C 编写的扩展模块")，类型提示被添加到扩展名为 .pyi 的存根"文件中.

In order to add type-hints to that file (which is an "Extension Module" as it is written in C), the type hints are added to a "stub" file with the extension .pyi.

该文件可以在 typeshed 中找到这是存根文件的集合.typeshed 还包含第三方模块的存根，这是一个历史遗留问题.由于 PEP-561 已被采用，因此不再需要.

That file can be found in the typeshed which is a collection of stub files. The typeshed also contains stubs for third-party modules which is a historical remnant. That is no longer needed since PEP-561 has been adopted.

存根文件包含普通 Python 模块的类型提示信息.完整的官方文档可以在关于 PEP 中的存根文件部分找到-484.

Stub files contain type-hinting information of normal Python modules. The full official documentation can be found in the section about stub-files in PEP-484.

例如，如果你有一个 Python 模块 mymodule.py 像这样:

For example, if you have a Python module mymodule.py like this:

def myfunction(name):
   return "Hello " + name

然后您可以通过存根文件 mymodule.pyi 添加类型提示.请注意，这里的省略号 (...) 是语法的一部分，因此下面的代码块确实显示了完整的文件内容:

Then you can add type-hints via a stub-file mymodule.pyi. Note that here the ellipsis (...) is part of the syntax, so the code-block below really shows the complete file contents:

def myfunction(name: str) -> str: ...

它们看起来与 C 头文件非常相似，因为它们只包含函数签名，但它们的使用完全是可选的.

They look very similar to C header files in that they contain only the function signatures, but their use is purely optional.

您也可以直接在 .py 模块中添加类型提示，如下所示:

You can also add type hints directly in the .py module like the following:

def myfunction(name: str) -> str:
   return "Hello " + name

但在某些情况下，您希望将它们分开存放在存根中:

But there are some cases where you want to keep them separate in stubs:

• 您希望保持您的代码与 Python 2 兼容并且不喜欢 # 类型:... 注释语法
• 您将函数注释用于其他用途，但仍想使用类型提示
• 您正在将类型提示添加到现有代码库中，并希望将现有文件中的代码搅动降至最低

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